Cam actuated twine knife



A ril 28, 1970 H. N. GRILLOT 3,503,776

CAM ACTUATED TWINE KNIFE Filed Oct. 14, 1968 4 Sheets-Sheet l INVENTOR HOMER N. GRIL LOT WC.M ,-n

ATT'Y.

H. N. GRILLOT CAM ACTUATED TWINE KNIFE 4 Sheets-Sheet 53 INVENTOR HOMER N. GRILLOT BY W ATT'Y.

April 28, 1970 Filed Oct. 14, 1968 April 1970 H. N. GRILLOT 3,508,776

CAM ACTUATED TWINE KNIFE Filed Oct. 14, 1968 4 Sheets-Sheet 5 INVENTOR HOMER N. GRILLOT ATT'Y.

April 28, 1970 H. N. GRILLOT CAM ACTUATED TWINE KNIFE 4 Sheets-Sheet 4 Filed Ocf 14, 1968 INVENTOR HOMER N. GRILLOT BY c. ATT'Y.

United States Patent O 3,508,776 CAM ACTUATED TWINE KNIFE Homer N. Grillot, Naperville, Ill., assignor to International Harvester Company, Chicago, Ill., a corporation of Delaware Filed Oct. 14, 1968, Ser. No. 767,330 Int. Cl. B65h 69/04 US. Cl. 289-14 4 Claims ABSTRACT OF THE DISCLOSURE A twine knife movably mounted on a twine knotter and actuated to effect a cutting stroke through the joint action of a cam mounted on the knotter cord holder and a follower mounted on the knife. The cam and follower are provided with intermeshing surfaces whereby the parts are maintained in planar alignment as the former acts upon the latter.

BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates generally to twine knives for baler knotters and more particularly to an improvement of the twine knife of the type disclosed and claimed in assignees copending patent application Ser. No. 739, 493, filed June 24, 1968.

The function of the cam actuated knife disclosed in the aforementioned patent application is to sever twine at a predetermined time in the tying cycle. Briefly, the knife is moved to a cocked position by the coordinated action of a cam and a cam follower, a compression spring oper ating to store potential energy as the knife is moved to the cocked position. When the cam clears the follower, the stored energy is released snapping the knife through a cutting stroke. In the aforementioned patent application, the companion surfaces of the cam and its follower extend normal to the direction of force application. Since the knife may be subjected to lateral forces during the cutting stroke, there is a possibility that the cam and follower may become misaligned. Moreover, as the companion surfaces become worn from use, a rounding of the surfaces may occur permitting the follower to slide axially over the cam.

The purpose of the present invention is to minimize the effect of misalignment and surface wear by particularly configurating the cam and its follower. By tapering the companion surfaces to extend obliquely with respect to the direction of cam travel, the cam intermeshes with the follower and thereby maintains the parts in planar alignment.

The objects of this invention briefly are to improve the operation and reliability of the cam actuated twine knife and to minimize the effect of Wear on the cam surfaces.

DESCRIPTION OF THE DRAWINGS FIGURE 1 is a perspective view of a knotter provided with the novel knife assembly of this invention;

FIGURE 2 is a top plan view of the cord holder assembly and knife assembly shown in FIGURE 1 with the knotter hook and the retaining finger diagrammatically illustrated;

FIGURES 3-6 are side elevation views of the cord holder assembly and knife assembly shown at various stages in the tying cycle; and

FIGURE 7 is a sectional view of the knife and cord holder assemblies and taken generally along the line 77 of FIGURE 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT In order to appreciate the principles of the present invention it is necessary to understand the operation of the typical twine knotter. With reference to FIGURE 1 a conventional knotter 10 is shown mounted above the baling chamber 11 of a baler. The knotter includes a frame 12 journally mounted on a knotter drive shaft 13 and bolted to the baler by means of anchor member 14. Anchor member 14 is a part of the breast-plate 16 which underlies the knotter 10 and has formed therein a longitudinal slot 18. The frame 12 supports the various components of the knotter 10 which includes a knotter hook assembly 19, a cord holding assembly 21, and a knife assembly 22. A breastplate finger 17 mounted on the breastplate 16 and extending across the slot 18 cooperates with the cord holder assembly 21 to retain twine during the tying cycle. The knotter components are driven in sequence by means of a conventional intermittant drive assembly shown generally as 23.

As shown in FIGURE 2 the cord holder assembly 21 includes a pair of notched discs 24 and 26 separated by a hub 27. The hub 27 and the rear disc 26 are integrally formed and the front disc 24 is secured to the outer face of the hub 27 by a plurality of screws 25 (see FIGURE 3). For the purposes of this invention the front and rear discs 24 and 26 may be considered identical, each having pairs of diametric deep and shallow twine carrying notches 28 and 29, respectively.

Interposed between the discs 24 and 26 is a keeper blade 31 which cooperates with the discs to grip ingly hold the twine during the bale forming cycle.

At the beginning of the baling operation twine retained in the shallow notch 29 extends around the cord holder assembly 21, through the deep notch 28 and thence around the breastplate finger 17. When the bale is formed in the baling chamber 11 the drive shaft 13 is rotated by conventional means (not shown) actuating the drive means 23 to drive the various knotter parts in the tying cycle. A twine needle (not shown) delivers twine to the cord holder assembly 21 thereby completely encircling the bale in the chamber 11. Next, the hook assembly 19 and the cord holder assembly 21 operating in sequence form a knot in strand end portions as follows: The hook 19 sweeps the pair of strand portions off the breastplate finger 17 while the cord assembly 21 rotates substantially from a strand receiving position to a strand holding position. As the cord assembly 21 approaches the strand holding position, the keeper blade 31 has wedged the twine carried in the shallow notches 29 between the discs 24 and 26, and the hook assembly 19 has returned to its home position, placing the assemblies in position for the final step of the tying cycle-the separation of the needle twine from the twine supply. The hook assembly 19, the cord holder assembly 21, and drive assembly 23 have been described only generally to indicate the environment of the knife assembly 22 which is the subject of this invention.

The knife assembly 22 includes an angulated blade holder 33 reciprocably mounted on the frame 12 by means of a mounting sleeve 34. The mounting sleeve 34 is bolted to the frame 12 as shown at 35 and has a square opening 36 (FIGURE 3) extending longitudinally therethrough. The holder 33 has a straight portion 37 complementary shaped to fit snugly into the square opening 36 and extends outwardly from the mounting sleeve 34 terminating at end 38. A compression spring 39 and a cap 41 are received on end 38 and held in assembled relation by a pin 42, the spring 39 acting between an end surface of the sleeve 34 and the cap 41. Another pin 40 affixed to the portion 37 is adapted to abut an opposite end surface of the sleeve 34 thereby limiting movement of the holder 33.

From the junction of the pin 40 and the portion 37, the holder 33 extends generally toward the axis of rotation of the cord holder assembly 21 terminating at end portion 43. Mounted on the end portion 43 and placed in side-byside relation are a cam follower 44 and a knife blade 45. As best seen in FIGURE 2, the cam follower 44 having a thickness greater than the blade 45 is positioned in close proximity to the front disc 24, but all three members, e.g., the front disc 24, the cam follower 44, and the knife blade, lie in parallel planes. The cam follower 44 is shaped to provide a profiled surface 46 adapted to cooperate with a cam 51 mounted on disc 24, described in detail below. The blade 45 has a tapered edge 47 disposed generally perpendicular to the longitudinal axis of the straight portion 37.

The cam 51, mounted on the front disc 24 by the set screws 25, provides the means for imparting oscillatory motion to the holder 33, and hence the blade 45. The earns 51, has a pair of cam surfaces 53, 53 arranged to engage the profile surface 46 of the follower 44 and thereby move the holder 33 to a cocked position against the bias of spring 39.

As the cord holder assembly 21 is rotated 180 from the twine receiving position (FIGURE 3) to the twine holding position (FIGURE 6) the cam 51 engages the follower 44 forcing the holder 33 outwardly against the bias of spring 39 (see FIGURE As the cord holder assembly 21 approaches the twine holding position, the knife assembly 22 reaches the cocked position. The final incremental movement of the cord holder assembly 21 carries the cam 51 clear of the follower 44 whereupon the force of spring 39 snaps the holder 33 back to its normal position, moving the blade through a cutting stroke. It should be noted that because the step-like action of the cord holder assembly 21, the diametrically situated cam surface 53, 53 act upon the follower 44 in alternate tying cycles.

To this point in the disclosure, the knife 22 is the same as that described in assignees copending patent application Ser. No. 739,493. The present invention is an improvement over the invention described and claimed therein and resides in the configuration of the cam surfaces 53 of the cam 51 and the profile surface 46 of the follower 44. As best seen in FIGURE 7 the surfaces 53 and 46 are tapered extending generally radially outwardly and axially outwardly with respect to the axis of rotation of the cord holder 21 and thereby presenting a contact surface 55 extending obliquely with respect to the direction of the force application indicated by the arrow F The tapered configuration provides for intermeshing of the cam 51 and the follower 44 as the former acts upon the latter. The interrneshing surfaces lock the follower 44 and cam 51 in planar alignment. The surfaces 53 and 46 are complementary shaped so that sufficient contact is provided to move the knife assembly 22 to its cocked position. The reaction force created by the spring 39 and pre sented graphically in FIGURE 7 as F provides a component force F extending parallel to the contact surface 55. Force F tends to maintain cam 51 and the follower 44 in alignment. Furthermore the tapered configuration of the surfaces 46 and 53 will result in a wear pattern that sharpens edges 46a and 53a of surfaces 46 and 53, respectively. In the embodiment of the invention as presented in the aforementioned patent application, the surfaces 46 and 53 extended in a direction normal to the direction of applied force F This configuration produced a situation conducive to the rounding of the shoulders corresponding to edges 46a and 53a of this embodiment. It is apparent that the self-sharpening charactristic of the cam and follower combination precludes the rounding of the shoulders and thereby greatly minimizes the adverse effect resulting from surface wear.

The operation of the knife assembly 22 will be described with reference to the FIGURES 2 to 6. Beginning with FIGURE 2, the cord holder and knife assemblies 21 and 22 are in their respective home positions. In this position,- a twine portion 56 passing through the deep notch 28 extends adjacent the knotter hook assembly 19 around 4 the breastplate finger 17 and thence around three sides of the bale being formed in the baling chamber 11. When the bale is completed the twine carrying needle delivers a twine portion 57 to the knotter assembly 21 laying it in the shallow notch 29 (see FIGURE 3). As the needle approaches its highest position the cord holder assembly 21 begins turning clockwise as viewed in FIGURE 4. At the same time the operation of the knotter hook assembly 19 sweeps the strands 56 and 57 off the breastplate finger 17 (see FIGURE 2) and joins the strands 56 and 57 in a knot in a manner well known in the art. Now as shown in FIGURE 4, rotation of the cord holder 21 brings the cam surface 53 of cam 51 into engagement with the profiled surface 46 of follower 44. Referring next to FIG- URE 5, continued movement of the holder assembly 21 causes the cam 51 to force the holder 33 outwardly to the cocked position compressing the compression spring 39. Meanwhile as the holder 33- is moved out, the action of the keeper bale 31 wedges strand 57 between the front and rear discs 24 and 26 gaining a secure hold thereon.

Next, the cord holder assembly 21 in the final increment of angular movement to its holding position, carries the cam 51 past the follower 44 allowing the spring 39 to snap the knife blade 45 through the cutting stroke. Just prior to the snapping action of the knife blade 45 the knotter hook assembly 19 has completed the knot and the only part of the tying cycle remaining is the severance of the portion 57 from the needle supply. In snapping back to its home position the knife assembly 22 causes the blade 45 to pass in the path of the oncoming strand 57 carried by the cord holder assembly 21. It should be emphasized that the cutting action is affected by the countermoving parts-the blade 45 moves toward the twine and the twine toward the blade 45. Now with the twine portion 57 cut and portion 56 released, the bound bale is forced rearwardly stripping the knot and ends from the knotter hook assembly 19.

Summarizing the present invention, the tapered configuration of the contact surfaces of a cam actuated knife assembly tend to maintain the correlated parts in alignment thereby minimizing the effects of surface wear.

What is claimed is:

1. In a twine knotter of the type having a frame:

a cord holder assembly rotatably mounted on said frame;

a cam mounted on said cord holder assembly for rotation therewith;

a knife assembly including a holder reciprocably mounted on said frame for movement in a straigh line path in a cocking stroke and in an opposite cutting stroke, a blade secured to said holder, and a follower mounted on said holder for engagement by said cam to move said holder through said cocking stroke, the improvement wherein said follower includes a surface opposing said cam and engageable therewith during said cocking stroke, said surface extending obliquely to said straight line path to resist movement of said follower laterally from said path, whereby said follower and said cam are maintained in engagement during said cocking stroke.

2. The subject matter of claim 1, wherein said surface extends generally radially outwardly and axially outwardly from the axis of rotation of said cord holder assembly.

3. In a twine knotter of the type having a frame:

a cord holder assembly rotatably mounted on said frame;

a cam mounted on said cord holder assembly for rotation therewith;

a knife assembly including a holder reciprocably mounted on said frame for movement in a straight line path in a cocking stroke and in an opposite cutting stroke, a blade secured to said holder, and a follower mounted on said holder for engage-ment by said cam to move said holder through said cocking stroke, the

improvement wherein said cam and said follower have opposed surfaces engageable to provide a force transmitting surface, said force transmiting surface extending obliquely to said straight line path to resist movement of said follower laterally from said path, whereby said follower and said cam are maintained in engagement during said cocking stroke. 4. The subject matter of claim 3, wherein said force transmitting surface extends generally radially outwardly and axially outwardly from the axis of rotation of said cord holder assembly.

References Cited UNITED STATES PATENTS LOUIS K. RIMRODT, Primary Examiner 

